Major shifts in employment between industries and between firms within industries usually accompany recessions. Although this observation suggests that exogenous changes in the optimal allocation of labor are an important source of aggregate employment fluctuations, the macroeconomic significance of such shocks has remained unknown. This paper empirically assesses the role of reallocation shocks for cyclical employment fluctuations, and investigates the relationship between inter- and intrasectoral employment flows. In an analysis of total employment and the share employed in manufacturing, we find that reallocation shocks account for the majority of the variance in employment shares and dispersion, while aggregate shocks' contribution is modest. The two shocks' impact on aggregate employment is sensitive to the identifying assumptions. However, under two of the three methods considered reallocation shocks account for over half of the variance in total employment. Including a measure of reallocation between firms in the manufacturing sector diminishes the effects of the intersectoral reallocation shocks on total and manufacturing employment, largely at the expense of the shocks to intrasectoral allocation. Together, the two reallocation shocks account for roughly half of the variance in total employment growth. We also find that permanent shifts in employment out of manufacturing depress job creation while increasing job destruction; by contrast, increases in employment reallocation between manufacturing establishments are associated with increases in both creation and destruction.